Acoustic properties of perforated plates and screens

International audience; In previous works, an acoustic model for Microperforated Insertion Unit (MIU), was developed to determine the input impedance of a system composed of a thin mesh (or screen) glued onto a perforated plate. An alternative approach is proposed by means of the equivalent fluid model of Johnson-Champoux-Allard involving five physical parameters: the tortuosity, the thermal and viscous characteristic lengths, the porosity and the flow resistivity. The input impedance of a multiple layer system can then be found by use of the transfer matrix method. Since the meshes have fairly simple structures, it was possible to model an elementary representative cell and to use calculat…